It is commonly understood that insulating oil is used in power transformers. A number of methods exist for various treatments relating to transformer oil. See Canadian Patent No. 1,227,026 (U.S. Pat. No. 4,498,992), which claims a process for treating contaminated transformer oil by heating the oil and passing it through an absorber, then chilling the oil, and Canadian Patent No. 2,143,580, a method for eliminating the oxidation of dielectric fluid using a continuous flow of inert gas and an expansion chamber. Also see U.S. Pat. No. 5,942,121, which claims a method for filtering and removing products of aging in oil using a mechanical filter, an adsorbent and degassing process, and U.S. Pat. No. 4,806,276, an additive for transformer oils comprised of a non-ionic fluorosurfactant and a halogenated hydrocarbon. Further, U.S. Pat. No. 6,193,786 claims a method and device for portable degasification, reducing the concentration of combustible gases in insulating oils, by forming a combustible gas-inert mixture and venting the mixture.
It is also known to use a gas or liquid analyzer with a transformer. See Canadian Patent No. 2,014,619, which claims a method and apparatus for analyzing gases in dissolved insulating oil, involving the use of separate gas stripping zones communicating with a flame ionization detector side and thermal conductivity detector side of a chromatograph. Also see Canadian Patent No. 1,082,774, which claims an apparatus and method for detecting and measuring fault gases in oil insulated transformers using a cell loop and hollow tubes, and Canadian Patent No. 2,054,616, which provides a method of determining the stability of insulating oil by ionizing and determining the concentration of free radicals in oil, and absorption spectra of oil before and after ionization of the oil.
Several technologies exist that attempt to prevent the deficiency presented by the absorption of elements in air that inhibits the service reliability and shortens the life expectancy of power transformers. Due to the direct contact with the outside atmosphere, the mineral insulating oil naturally dissolves 10% air in volume. Under the impact of heat and electrical stress, certain vulnerable components of this complex blend of hydrocarbons decomposes and generates broken molecules, known as free radicals, having each an unpaired electron. Since dissolved oxygen is also a free radical with two unpaired electrons, its contamination with the broken hydrocarbon chains generates a variety of decay products that irreversibly damage the solid insulation also part of the transformer. In one known method, oxidation inhibitors are added to the insulating oil in order to increase its resistance to oxidation. These additives improve the chemical stability for a certain period of time. Another known system is to seal the transformer by using a flexible membrane or a static nitrogen membrane cushion above the oil, both of which are prone to failure, and of necessity constrain the ability of the oil to expand and contract in “use” conditions; or to vent gases produced during use.